For a second straight day, onshore winds have blown thick fog ashore along the San Diego County coastline, prompting a dense fog advisory from the National Weather Service. Forecasters say the fog will reduce visibility to less than a half mile in places overnight, and that it could slow traffic on Interstates 5 and 8. The fog also could flow several miles inland in south county, as it did last night.

The view from the boardwalk in Mission Beach on Thursday night. — Mark Moll

The view from the boardwalk in Mission Beach on Thursday night.
/ Mark Moll

The fog will clear in most places by mid-morning on Saturday, and daytime highs will rise into the upper 60s along the coast. Skies are expected to be mostly clear on New Year's Eve. A growing ridge of high pressure will send the temperature as high as 78 on Sunday in San Diego.